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Overview: Glutamine is available over the counter as a dietary supplement. It is used for various reasons, although its benefits for many of these uses are not well defined. Glutamine is an amino acid, which is a building block for protein. It has many different effects in the body, including supporting the health of your gut and immune system. Common side effects may include constipation, headache, nausea, vomiting, or upset stomach. Before taking glutamine, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is glutamine used for?

Glutamine is a dietary supplement that is used for various reasons, although its benefits for many of these uses are not well defined. Some common reasons that people use glutamine include the following.

Glutamine may also be used for other conditions as determined by your health care provider.

Glutamine is also available as a prescription product that is used for sickle cell disease. See L-Glutamine (Endari) for more information. Only use the product prescribed or recommended for you by a health care provider.

Note: The FDA has not reviewed glutamine dietary supplements for safety and effectiveness. Learn more about dietary supplements here.

How does glutamine work (mechanism of action)?

Glutamine is an amino acid, which is a building block for protein. It has many important functions in the body, such as supporting the health of your gut and immune system and helping your body make antioxidants.

Your body usually makes enough glutamine to meet your needs. You may also get small amounts of glutamine from your diet, such as from wheat, corn, soy, and milk. Your body needs more glutamine when it is under severe stress, such as when you are very sick or if you participate in regular, heavy exercise. In these situations, your body may not be able to make enough glutamine to meet your needs. 

Taking glutamine can help increase glutamine levels in your body. This may help support the cells in your gut and immune system during times of severe illness. Some examples of severe illness include recovering from major surgery, having serious burns or a serious infection, or being treated for cancer.

People with certain health conditions, such as HIV or inflammatory bowel disease (IBD), sometimes take glutamine to improve gut health and increase weight gain. Some people also use glutamine to support their muscles during regular, heavy exercise. But the benefits of glutamine for these uses are not well defined.

How should I store glutamine?

You should store glutamine according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of glutamine?

The most common side effects of glutamine are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.

  • Constipation
  • Headache
  • Nausea or vomiting
  • Upset stomach

There may be other side effects of red yeast rice that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of glutamine?

While less common, the most serious side effects of glutamine are described below, along with what to do if they happen.

Severe Allergic Reactions. Glutamine may cause allergic reactions, which can be serious. Stop taking glutamine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use glutamine?

Allergies to Ingredients. People who are allergic to any of the following should not take glutamine.

  • Glutamine
  • L-glutamine
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific glutamine products they stock.

What should I know about glutamine before using it?

Glutamine as a dietary supplement cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep glutamine out of the reach of children.

If you are using glutamine powder, use an appropriate measuring device to measure the powder, such as the device included with the product. Read the label carefully and measure the amount stated on the label. Mix the powder with a glass of liquid, such as water or juice.

The FDA has not tested glutamine dietary supplements to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using glutamine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if glutamine is right for you.

In particular, make sure that you discuss any of the following.

Pregnancy. It is not known if or how glutamine could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if glutamine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does glutamine interact with foods or drinks?

There are no known interactions between glutamine and foods or drinks.

It is unknown if drinking alcohol will affect glutamine.

Does glutamine interact with medicines (drug interactions)?

There are no known interactions between glutamine and medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

The interactions between glutamine and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with glutamine is incomplete. Always check with your health care provider before taking glutamine with any medicines.

Overdose/Missed Dose

What should I do if I accidentally use too much glutamine?

If you or someone else has used too much glutamine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

The correct dose of glutamine may be very different depending on your reasons for using it. Read the product label closely and speak with a health care provider about how to use glutamine safely. If you miss a dose, skip the missed dose. Do not take double or extra doses.